Researchers found that the brain stimulation technique only helps those with high maths anxiety, zapping the brain can have completely opposite effects in individuals with low maths anxiety.

Roi Cohen Kadosh at the University of Oxford and colleagues have shown that effects of brain stimulation depend on your personality.

Previous research has shown that a type of non-invasive brain stimulation called transcranial direct current stimulation (tDCS) - which enhances brain activity using an electric current - can improve mathematical ability when applied to the dorsolateral prefrontal cortex, an area involved in regulating emotion.

To test whether personality traits might affect this result, Kadosh's team tried the technique on 25 people who find mental arithmetic highly stressful, and 20 people who do not, 'New Scientist' reported.

They found that participants with high maths anxiety made correct responses more quickly and, after the test, showed lower levels of cortisol, an indicator of stress.

On the other hand, individuals with low maths anxiety performed worse after tDCS. The study was published in Journal of Neuroscience.